The Third Generation Partnership Project (3GPP) Release 8 specifies for circuit switched fallback (CSFB) when a circuit managed (CM) transmission is delivered to a device camped on the long term evolution (LTE) network since LTE is a packet switched (PS) data based technology. By using CSFB, the device may select to a third generation (3G) radio access technology (RAT), such as the Universal Mobile Telecommunications System (UMTS), or a second generation (2G) RAT, such as the Global System for Mobile Communications (GSM), in order to receive the incoming CM transmission. In other words, when an LTE device is used to make or receive a CM transmission such as a voice call, Supplementary Service (SS) transaction, Unstructured Supplementary Service Data (USSD) transaction, the LTE device will fall back to a 3G or 2G RAT (collectively, hereinafter, referred to as a “legacy RAT”) in order to complete the CM transmission.
When a CM transaction is supported by CSFB, the LTE device (i.e. mobile terminal, or user element (UE)) will switch from the LTE network to the legacy RAT network where the transaction can be performed. This applies to non-call related CM transactions as well, such as an Supplementary Service (SS) transactions, Unstructured Supplementary Service Data (USSD) transactions, etc. Since most of these non-call related transactions are short in duration and may arrive in frequent intervals, the UE will fall back from the LTE network to the legacy RAT network in order to receive the transaction, camp back on the LTE network upon completion of the transaction, fall back to the legacy RAT network for the next transaction, etc. This leads to a high load on LTE and legacy RAT networks by performing repetitive inter-RAT (IRAT) handover or redirection procedure involving the movement of the UE from LTE network to a legacy RAT network and vice versa. In addition to the high loads imposed on the networks, this process leads to increased power consumption in the UE and a deterioration in the end user experience as the high number of IRAT handovers or redirections will consume larger amounts of time.